I really don't care about the number of stars my project has if I'm going to make something private. It's not like most important projects sticks out by a very significant amount of stars. What percentile would? And what percentile of these occurances are on this scale? (basically none according to the article)
I'd care more about the number of active contributors who will loose access, if I did care for a message like that.
This is pretty significant because lots of downstream users and distribution maintainers use the watching feature to get release and security advisory notifications. If this had happened secretly it's possible that a security release would be delayed because they didn't see the announcement early enough. (In fact, in the article they mention they had a security advisory recently -- so it's possible the above scenario has already happened.)
The UI warns you something serious is going to happen with bold text on a separate line.
It makes you type the full path of the affected object.
His explanation for what he was doing in the first place (making a README file private) doesn't make the slightest bit of sense.
It's a PR stunt for a startup company.